1. Field of the Invention
This invention relates to molded earplugs and, more particularly, to molded earplugs which are easily detectable by X-rays or other scanning methods.
2. Background of the Prior Art
Earplugs and other hearing protectors have become standard equipment in many industries where there is continuous exposure to the excessive noises generated by manufacturing or processing equipment. These earplugs and hearing protectors provide inumerable benefits to the employees working in the processing line and reduce health-related costs to the employer. However, the taking of foreign objects such as earplugs into certain process areas is not without risk. When used on a food or beverage processing line, a pharmaceutical line, or any other processing line where there is exposure to consumable items, there is a risk that an earplug may fall into the foodstuff, beverage, pharmaceutical, or other substance being processed. Although these processing lines are invariably provided with detectors of a sort for detecting metallic objects, earplugs which are made of a foam material, soft rubber, or plastic cannot be detected by such safety systems.
In order to prevent the earplug from falling into the foodstuff, it has been the practice to provide a pair of earplugs on opposite sides of a length of cord. In this instance, if one earplug becomes loose, it will remain retained on the end of the length of cord. It will not fall into the foodstuffs on the processing line. However, it is possible for the cord to become separated from the earplug and the earplug to become dislodged from the ear of its wearer. In such an instance, the earplug could fall into the foodstuff and would not be detected by normal detection means.
To remedy the risk of a nondetectable earplug falling into the foodstuffs on a processing line, Salmon, European Patent Publication No. 244 979, teaches the use of a metal ferrule provided on the end segments of the length of cord for use in a corded earplug. The metal ferrule is forced into the earplug so that the ferrule is wholly contained within the plug. Because the metal ferrule is crimped onto the cord, Salmon claims that it is very unlikely that the length of cord will ever become detached from the ferrule.
Although an improvement over the prior corded earplugs, the Salmon earplugs are nevertheless confronted with deficiencies. First, the metal ferrule requires a particular material for the cord composition. A PVC or other plastic cord which does not transmit noise to the extent that an ordinary cord does is not compatible with the metal ferrule. If the metal ferrule were placed on the ends of a PVC or other plastic cord, there is a much greater possibility of the cord separating from the plug. Second, should the cord and earplug separate, the chances are great that the detectable part of the product, that being the metal ferrule, will remain on the cord. As a result, the employee on the line is left with a loose undetectable plug which could fall into the foodstuff. Finally, the use of the metal ferrule in the earplug limits the flexibility of the earplug. This hinders the insertion of the earplug into the wearer's ear as well as causing a degree of discomfort to the wearer during normal wear.